It didn't have any problem to find the router and connect to it and I could ping the router successfully. Then I started "sudo apt-get update". Ran fine, several OKs, but hung before the end. I opened another console and tried again to ping the router and - nothing - not found - dead.

According to the network widget in the tray, iwconfig and the router list of connected devices the connection is still alive.

This happens everytime. Right after login in the connection is alive and working for a few seconds then feigning death.